1. Field of the Invention
The present invention relates to a method of fabricating a superconducting junction using an oxide superconducting thin film, and more particularly, to a method of fabricating a superconducting junction by integrating a first oxide superconducting thin film, a non-superconducting barrier thin film, and a second oxide superconducting thin film in series on an oxide single crystal substrate.
2. Description of the Prior Art
Generally, there must be fabricated a superconducting junction in order to apply an oxide superconducting thin film for an electronic device. There show various kinds of superconducting junction structure so far, the simplest one is a tunnel type Josephson junction.
The tunnel type Josephson junction is composed of a three layer thin film structure according as a non-superconducting barrier layer is inserted in the form of sandwich between a pair of superconducting thin films which performs a superconducting electrode function. Typically, such a tunnel type Josephson junction is fabricated by the process of depositing a first superconducting thin film, a non-superconducting barrier thin film, and a second superconducting thin film successively on the substrate.
Conventionally, there are performed a process of depositing a first YBCO superconducting thin film and a second YBCO superconducting thin film, a process of fabricating a non-superconducting barrier thin film using a YBCO superconducting thin film and a metal or oxide thin film whose the composition is different from the YBCO thin film in order to fabricate a tunnel type Josephson junction.
It is difficult to fabricate a good quality tunnel type Josephson junction because the tunnel type Josephson junction fabricated as above generates a stress by means of the difference of a lattice constant and a thermal expansion coefficient between a superconducting thin film and a non-superconducting barrier thin film. Accordingly, there is necessary a process using a barrier thin film having the composition equal to both a first superconducting thin film and a second superconducting thin film in order to improve the performance of the tunnel type Josephson junction.